Merge pull request #1 from raonism/develop

example source code.
1. Toogle to making guide mode (w/ extension button, popup window.. no more content script)
2. Emphasize the element on mouse overed (moved)
3. Add extension button icon
merged with Lyu's files
Merge pull request #2 from iimplicit/dev_guideBalloon

Dev guide balloon
Get rid of useless(commented) codes.
Merge pull request #3 from LyuGGang/develop

Get rid of useless(commented) codes.